<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>

    /*
    * 基本数据类型有5个
    * number string boolean undefined null
    * 引用数据类型一个 object
    */
    let username = prompt('请输入您的姓名:')
    // 模板字符串
    document.write(`您的姓名是:${username}`)

    // 类型检查
    let age = 10
    console.log(typeof age);

    // string
    let gender = '女'
    console.log(typeof gender);

    // boolean
    let isSuccess = false
    console.log(typeof isSuccess);

    // 未定义
    let number
    console.log(typeof number);

    // null是对象类型
    number = null
    console.log(typeof number);

    // 特殊
    console.log(null + 1)
</script>
</body>
</html>